Wastewater-collection tanks of sanitary arrangements are used for stationary units, for example, water closet (“WC”) arrangements for events or construction sites, and for mobile units, such as sanitary arrangements in motor vehicles or track-bound vehicles, and serve to receive the wastewater from toilets, washbasins, or other sanitary arrangements and to collect said wastewater for a certain period of time. Such a wastewater-collection tank has to be emptied at regular intervals. This emptying often takes place by virtue of an emptying valve being opened and of the wastewater being discharged, through a discharge opening, into an appropriate catching device, which is arranged beneath the discharge opening of the wastewater-collection tank.
The advantage with this emptying method is that virtually complete emptying is achieved, resulting in a high level of hygiene in the tank since there is no residual wastewater in the tank. In addition, this emptying method provides for an emptying operation that is very reliable in relation to blockages, which often occurs on account of solids, such as paper towels or the like, in sanitary arrangements, this reliability being achieved as it is possible to realize a large outlet passage at the outlet opening. Such an outlet passage is described in technical terms by means of a ball-passage dimension, that is to say, the diameter of a ball which fits through the outlet passage. Ball-passage dimensions of more than 30 mm or 40 mm are often advantageous in order for the outflow from the outlet opening to take place in a blockage-free manner.
It is known, for example, for coaches to be positioned, for this purpose, above an opening made in the ground, in order for the draining wastewater to pass into said opening. The disadvantage with this procedure is that the coach is sometimes not placed precisely in position, as a result of which the discharge opening does not end up located precisely above the opening in the ground and therefore the region around the opening in the ground is contaminated.
DE 20 2015 103 442 discloses a disposal device for the wastewater tank of coaches, use being made here, instead of such an opening in the ground, of a mobile receptacle that allows improved placement beneath the discharge opening of the wastewater-collection tank. Although, as a result, the positioning accuracy is improved, it is nevertheless the case that the poor visibility can result in incorrect operation, which leads to contamination. In addition, the device already known from DE 20 2015 103 442 U1 requires a catching hopper, which is contaminated by the wastewater being discharged and, therefore, renders subsequent cleaning necessary.
DE 20 2015 105 495 U1 discloses a further development for the disposal of the wastewater from wastewater-collection tanks in coaches. This document proposes using an opening in the ground, said opening being designed in a specific manner and being covered by a specifically shaped grate, to receive the wastewater in a stationary arrangement, and describes various auxiliary means in order to position the discharge opening precisely above said opening in the ground. The technology described therein makes it easier to position the coach and the discharge opening from the wastewater-collection tank installed thereon. Nevertheless, it is also occasionally the case that contamination and odor-related problems occur with this method of emptying the wastewater-collection tank.
DE 89 00 672 U1 discloses a device for draining wastewater-collection tanks in residential areas. This device is designed in a specific manner in order to achieve air-free suction extraction, for which purpose a suction-extraction tube is guided into a container which is arranged in a floating state in the wastewater-collection tank. The disadvantage with this configuration is that the feed of the wastewater from the wastewater-collection tank into the suction-extraction arrangement has to be arranged at a considerable height in relation to the tank floor, in order to ensure that, on account of the hydraulic conditions, the wastewater flows. This means that suction extraction of the wastewater is possible only up to a certain level above the floor, and a considerable amount of residual wastewater remains following suction extraction in the wastewater-collection tank. This may well be functionally acceptable for stationary applications, in which use is made of large wastewater-collection tanks, but it is wholly inadequate for applications in which the available space is at a premium, and, therefore, the full capacity of the wastewater-collection tank has to be utilized, because, in the case of this space-saving application, it has to be possible for suction extraction from the wastewater tank to be as complete as possible.
DE 20 2012 003 064 U1 discloses a wastewater arrangement for camping vehicles, it being possible for the wastewater to be discharged via a discharging nozzle. This discharging nozzle is directed downward, in the center-of-gravity direction, from the floor of the wastewater-collection tank and thus provides for complete emptying of the wastewater-collection tank. The disadvantage with this configuration, however, is that the outflow direction renders a corresponding catching device necessary, and the operation of discharging the wastewater overall can be laborious and unhygienic.